Stonex Solutions

In March 2022 Stonex had the opportunity to carry out a series of surveys inside and outside the “Torretta Viscontea” located in the Monza Park.

The goal was to obtain a detailed and geo-referenced 3D model of the building in order to produce accurate elevations and floor plans of interiors and exteriors.

These surveys were carried out with the partnership of the Consorzio Parco Villa Reale as part of a redevelopment project for the Tower itself.

Torretta Viscontea – historical notes

The building with neo-Gothic forms was designed by Canonica in the early 1800s, but the project was only carried out in 1822, when Giacomo Tazzini decided to exploit the rural building of the old Tuscan farmhouse to create a “Gothic” building with a tower.

The building develops on two floors with a side portico and a tower with a lookout at its top.
An engraving by Frederic Lose dated 1826 and entitled “La Tour dans le jarden”, shows the tower finally completed and identical to how it is today. Therefore it can be deduced that the completion date of the works is between the end of 1824 and the beginning of 1826.

 Surveys and Data

Different Stonex instruments and software were used to obtain a complete and detailed interior and exterior project.

The entire range of Stonex Laser Scanners (X300, X150 and XH120) has been used to obtain high quality orthomosaics and a reliable survey from a metric point of view starting from the digital twin of the building.

A photogrammetric survey carried out with a DJI drone made it possible to collect 230 photos and to integrate the data on the ground with the aerial one.

X300 laser scanner, given its range of 300m and the ability to create very dense and extremely precise point clouds, was used for outdoor data collection, in particular to capture the details and decorations of the tower facades.

X150, with a minimum range of 20cm and a maximum of 150m, is a light and versatile instrument and has been used to collect data both indoors and outdoors. The clouds produced by X150 were then colored thanks to an integrated 360 HDR camera. Finally, the XH120 portable laser, with its SLAM (Simultaneous Localization And Mapping) technology, proved to be invaluable in being able to return a precision plan of the walls and to collect data inside the narrow tower. The data from the XH120 also allowed a perfect point clouds registration of indoor and outdoor.

Together with the 3D survey, a topographic survey was carried out with the S990A GNSS receiver and R20 total station in order to georeference all the collected data with maximum precision. The S990A GNSS receiver was also used to measure the Ground Contol Points to be associated with the aerial photogrammetric data.

The Stonex Cube-a software has been an excellent ally in data collection in the field thanks to its simple and intuitive interface.

All these data were processed in the office in the following days using the Cube-manager, Cube-3d and Stonex Reconstructor software.

Stonex Reconstructor was used for the filtering and registration of point clouds from Laser Scanner while with Cube-3d it was possible to create the final project of merging all the collected data as it is able to read a wide range of formats. Cube-3d was able to:

• Manage the complete photogrammetric project (photo, 3d model, orthophoto)
• Import point cloud files from laser scanners (since it can handle clouds generated by any source)
• Import and manage the CAD data of the topographic survey (points, polylines, etc.)

The final result confirms that the integration between laser scanner data (TLS and SLAM) and photogrammetric survey (aerial) allows to obtain a geometrically reliable digital 3D model enriched with color data, perfectly functional to the needs of Consorzio Parco Villa Reale.

Conclusions

In recent years, new technologies have become valuable tools for analyzing the state of conservation of historic buildings. Geomatics offers solutions for integrated digital surveys and heritage documentation (point based methods, image-based photogrammetry and their combination) which, unlike a traditional survey, allow you to save time and have a high level of accuracy even in cramped of badly preserved structures.

For this reason, laser scanner and aerial photogrammetry surveys enhanced by GNSS and total station positioning systems can be used for the production of detailed and optimally georeferenced 3D models.

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